Scale deposit, for example, in the form of calcium carbonate in industrial boilers cooling towers, heat exchangers and the like, is a very common and serious problem. Various types of water treatment chemicals have been proposed including chelants (e.g., EDTA and NTA), lignosulfonates, polyphosphates, polyacrylates, polymethacrylates, maleic anhydride copolymers, polymaleic anhydride, phosphate esters, and phosphonates (see Principles of Industrial Water Treatment, Drew Chemical Corporation, 1977, pp. 81-84).
U.S. Pat. No. 4,277,359 to R. J. Lipinski is one example of corrosion and mineral scale deposition inhibition in which a water soluble polymer comprising acrylic acid is used in combination with minor amounts of phosphorous acid and derivatives.
More recent U.S. Pat. No. 4,306,991 to C. M. Hwa advocates use of a copolymer of styrene sulfonic acid and maleic anhydride or maleic acid, along with a water soluble organophosphonic acid compound.